NIH clinical trial evaluates mixed COVID-19 vaccine schedules

June 3, 2021

The National Institutes of Health (NIH) has started a Phase 1/2 clinical trial in which adult volunteers who have been fully vaccinated against COVID-19 will receive booster doses of different COVID-19 vaccines to determine the safety and immunogenicity of mixed boosted regimens.

The National Institute of Allergy and Infectious Diseases (NIAID), part of NIH, is leading and funding the study through the Infectious Diseases Clinical Research Consortium, a clinical trials network that encompasses the Institute's long-standing Vaccine and Treatment Evaluation Units (VTEUs).

The trial will include approximately 150 individuals who already have received one of the three COVID-19 vaccine regimens currently available under FDA emergency use authorization in the United States: the Janssen COVID-19 vaccine (also referred to as the Johnson & Johnson vaccine, or Ad26.COV2-S), the Moderna COVID-19 vaccine (also known as mRNA-1273), and the Pfizer-BioNTech COVID-19 vaccine (also known as (BNT162b2). Each vaccine group will enroll about 25 people who are 18-55 years old and approximately 25 people who are 56 years and older. Between 12 and 20 weeks following their initial vaccination regimen, participants will receive a single booster dose of the Moderna COVID-19 vaccine as part of the trial.

People who have not yet received an FDA authorized COVID-19 vaccine are also eligible to enroll in the trial in a separate cohort. Initially, these volunteers will receive the two-dose Moderna COVID-19 vaccine regimen and will be assigned to receive a booster dose of a vaccine about 12 to 20 weeks later.

All trial participants will be followed for one year after receiving their last vaccination as part of the study. The Initial trial results are expected in late summer 2021.

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